Opinion | Free speech disappears in Turkey. So does democracy.

The legislation, approved by parliament on Oct. 13 with backing from Mr. Erdogan’s ruling Justice and Development Party and its allies, is clearly intended to silence critics before next year’s presidential election, providing the government with new tools to criminalize journalism and online activity. The law imposes penalties for disseminating “misleading information,” the definition of which is left ominously vague, and adding a new article to the Turkish Penal Code: “Any person who publicly disseminates untrue information concerning the internal and external security, public order and public health of the country with the sole intention of creating anxiety, fear or panic among the public, in a manner that is capable of disrupting public peace, shall be sentenced to imprisonment from one to three years.” If the perpetrator “commits the offense by concealing his real identity or within the framework of the activities of an organization,” the sentence is to be increased by half.

Misinformation and disinformation are challenges for every nation. But Turkey’s new law is a license to muzzle free expression. It will give prosecutors wide latitude to accuse legitimate journalists, as well as others, of having an “intention” to create anxiety, fear or panic — and throw them in jail. The Venice Commission, the Council of Europe’s expert legal body, noted in an Oct. 7 opinion that the wording of the new law is “very broad.” It added, “Does a post on Facebook accessible only to one’s Facebook friends amount to ‘public dissemination’? Or does an unsolicited e-mail sent to a specific e-mail address … ?” The experts warned the law could have a “chilling effect.”

Some independent journalists in Turkey have survived with online newsletters, podcasts and videos, despite existing restrictions. The new law “greatly increases the extent” to which tech companies “can be held criminally, administratively, and financially liable,” and introduces severe sanctions for failure to comply with content-blocking, removal requests or demands for data from the government, according to Human Rights Watch and Article 19, a group that defends free expression. Burak Erbay, a lawmaker who opposed the bill, declared: “You only have one freedom; it is the phone in your pocket … if this law passes, you can break your phones like this, you will not need to use it.” He took a hammer and smashed a cellphone.

We recently met with Kemal Kilicdaroglu, leader of the opposition Republican People’s Party, who objected to Mr. Erdogan’s practice of jailing those who speak out against him. “We cannot talk about democracy if the country puts their journalists in jail,” he told us. “Nobody should be in prison because of what they think.”

Nor can you build a thriving nation by locking up its most outspoken voices. The new law marks another backward step for Turkey.